The difficulty, of course, is that self-interest (even self-love) can and does interfere with the exercise of calm reason, particularly when it comes to deciding whether another person has violated (or soon may violate) the law of nature in a situation that involves one’s own self-interest. The lack of a “known and indifferent judge” in the state of nature, “with authority to determine all differences according to the established law,” leaves everyone both to judge and to carry out punishments for violations of the law of nature. The right and power to do so, however, result in the state of war that drives human beings out of the state of nature and into an agreement to enter into civil society.
In other words, the right and power of every individual to be his or her own judge in deciding whether someone else has acted contrary to reason is one of the reasons why living in a state of nature is not possible. Individuals must abandon the state of nature and enter into civil society in order to enjoy peace, security, and protection of property. In leaving the state of nature, everyone gives up the power “to do whatsoever he thinks fit for the preservation of himself, and others within the permission of the law of nature.” Everyone also gives up the power to punish offenses against the law of nature. In return, however, everyone acquires the right be governed by “established standing laws” and have controversies decided by “indifferent and upright judges.”
In sum, Locke explained the dangers to peace and security if self-interested individuals have the power of judging in their own cases. He also explained why judging is one of the important functions of government. However, Locke did not contend that judging must be separated from other governmental functions. To the contrary, he described the activities of judging and executing the laws as being closely related. Neither did Locke contend that social contract theory necessarily supports republican government. Indeed, he suggested that social contract theory can be compatible with various forms of government, including a limited monarchy
Many of the ideas in Locke’s Second Treatise about the legitimate foundations of government were revolutionary and hence considered dangerous. Social contract theory, after all, undermined the theory of divine right of kings. The Second Treatise was published anonymously in 1690, and Locke never claimed authorship. (Laslett edition). By the mid-Eighteenth Century, however, Lockean principles were part of the mix in the groundbreaking thinking about government taking place in the North American colonies.